content: // Protocol Buffers - Google's data interchange format
  // Copyright 2008 Google Inc.  All rights reserved.
  // https://developers.google.com/protocol-buffers/
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  package com.google.protobuf.util;
  
  import static com.google.common.math.IntMath.checkedAdd;
  import static com.google.common.math.IntMath.checkedSubtract;
  import static com.google.common.math.LongMath.checkedAdd;
  import static com.google.common.math.LongMath.checkedMultiply;
  import static com.google.common.math.LongMath.checkedSubtract;
  import static com.google.protobuf.util.Timestamps.MICROS_PER_SECOND;
  import static com.google.protobuf.util.Timestamps.MILLIS_PER_SECOND;
  import static com.google.protobuf.util.Timestamps.NANOS_PER_MICROSECOND;
  import static com.google.protobuf.util.Timestamps.NANOS_PER_MILLISECOND;
  import static com.google.protobuf.util.Timestamps.NANOS_PER_SECOND;
  
  import com.google.protobuf.Duration;
  import java.text.ParseException;
  import java.util.Comparator;
  
  /**
   * Utilities to help create/manipulate {@code protobuf/duration.proto}. All operations throw an
   * {@link IllegalArgumentException} if the input(s) are not {@linkplain #isValid(Duration) valid}.
   */
  public final class Durations {
    static final long DURATION_SECONDS_MIN = -315576000000L;
    static final long DURATION_SECONDS_MAX = 315576000000L;
  
    /** A constant holding the minimum valid {@link Duration}, approximately {@code -10,000} years. */
    public static final Duration MIN_VALUE =
        Duration.newBuilder().setSeconds(DURATION_SECONDS_MIN).setNanos(-999999999).build();
  
    /** A constant holding the maximum valid {@link Duration}, approximately {@code +10,000} years. */
    public static final Duration MAX_VALUE =
        Duration.newBuilder().setSeconds(DURATION_SECONDS_MAX).setNanos(999999999).build();
  
    private Durations() {}
  
    private static final Comparator<Duration> COMPARATOR =
        new Comparator<Duration>() {
          @Override
          public int compare(Duration d1, Duration d2) {
            checkValid(d1);
            checkValid(d2);
            int secDiff = Long.compare(d1.getSeconds(), d2.getSeconds());
            return (secDiff != 0) ? secDiff : Integer.compare(d1.getNanos(), d2.getNanos());
          }
        };
  
    /**
     * Returns a {@link Comparator} for {@link Duration}s which sorts in increasing chronological
     * order. Nulls and invalid {@link Duration}s are not allowed (see {@link #isValid}).
     */
    public static Comparator<Duration> comparator() {
      return COMPARATOR;
    }
  
    /**
     * Compares two durations. The value returned is identical to what would be returned by:
     * {@code Durations.comparator().compare(x, y)}.
     *
     * @return the value {@code 0} if {@code x == y}; a value less than {@code 0} if {@code x < y};
     *     and a value greater than {@code 0} if {@code x > y}
     */
    public static int compare(Duration x, Duration y) {
      return COMPARATOR.compare(x, y);
    }
  
    /**
     * Returns true if the given {@link Duration} is valid. The {@code seconds} value must be in the
     * range [-315,576,000,000, +315,576,000,000]. The {@code nanos} value must be in the range
     * [-999,999,999, +999,999,999].
     *
     * <p><b>Note:</b> Durations less than one second are represented with a 0 {@code seconds} field
     * and a positive or negative {@code nanos} field. For durations of one second or more, a non-zero
     * value for the {@code nanos} field must be of the same sign as the {@code seconds} field.
     */
    public static boolean isValid(Duration duration) {
      return isValid(duration.getSeconds(), duration.getNanos());
    }
  
    /**
     * Returns true if the given number of seconds and nanos is a valid {@link Duration}. The {@code
     * seconds} value must be in the range [-315,576,000,000, +315,576,000,000]. The {@code nanos}
     * value must be in the range [-999,999,999, +999,999,999].
     *
     * <p><b>Note:</b> Durations less than one second are represented with a 0 {@code seconds} field
     * and a positive or negative {@code nanos} field. For durations of one second or more, a non-zero
     * value for the {@code nanos} field must be of the same sign as the {@code seconds} field.
     */
    public static boolean isValid(long seconds, int nanos) {
      if (seconds < DURATION_SECONDS_MIN || seconds > DURATION_SECONDS_MAX) {
        return false;
      }
      if (nanos < -999999999L || nanos >= NANOS_PER_SECOND) {
        return false;
      }
      if (seconds < 0 || nanos < 0) {
        if (seconds > 0 || nanos > 0) {
          return false;
        }
      }
      return true;
    }
  
    /** Throws an {@link IllegalArgumentException} if the given {@link Duration} is not valid. */
    public static Duration checkValid(Duration duration) {
      long seconds = duration.getSeconds();
      int nanos = duration.getNanos();
      if (!isValid(seconds, nanos)) {
          throw new IllegalArgumentException(String.format(
              "Duration is not valid. See proto definition for valid values. "
              + "Seconds (%s) must be in range [-315,576,000,000, +315,576,000,000]. "
              + "Nanos (%s) must be in range [-999,999,999, +999,999,999]. "
              + "Nanos must have the same sign as seconds", seconds, nanos));
      }
      return duration;
    }
  
    /**
     * Convert Duration to string format. The string format will contains 3, 6, or 9 fractional digits
     * depending on the precision required to represent the exact Duration value. For example: "1s",
     * "1.010s", "1.000000100s", "-3.100s" The range that can be represented by Duration is from
     * -315,576,000,000 to +315,576,000,000 inclusive (in seconds).
     *
     * @return The string representation of the given duration.
     * @throws IllegalArgumentException if the given duration is not in the valid range.
     */
    public static String toString(Duration duration) {
      checkValid(duration);
  
      long seconds = duration.getSeconds();
      int nanos = duration.getNanos();
  
      StringBuilder result = new StringBuilder();
      if (seconds < 0 || nanos < 0) {
        result.append("-");
        seconds = -seconds;
        nanos = -nanos;
      }
      result.append(seconds);
      if (nanos != 0) {
        result.append(".");
        result.append(Timestamps.formatNanos(nanos));
      }
      result.append("s");
      return result.toString();
    }
  
    /**
     * Parse from a string to produce a duration.
     *
     * @return A Duration parsed from the string.
     * @throws ParseException if parsing fails.
     */
    public static Duration parse(String value) throws ParseException {
      // Must ended with "s".
      if (value.isEmpty() || value.charAt(value.length() - 1) != 's') {
        throw new ParseException("Invalid duration string: " + value, 0);
      }
      boolean negative = false;
      if (value.charAt(0) == '-') {
        negative = true;
        value = value.substring(1);
      }
      String secondValue = value.substring(0, value.length() - 1);
      String nanoValue = "";
      int pointPosition = secondValue.indexOf('.');
      if (pointPosition != -1) {
        nanoValue = secondValue.substring(pointPosition + 1);
        secondValue = secondValue.substring(0, pointPosition);
      }
      long seconds = Long.parseLong(secondValue);
      int nanos = nanoValue.isEmpty() ? 0 : Timestamps.parseNanos(nanoValue);
      if (seconds < 0) {
        throw new ParseException("Invalid duration string: " + value, 0);
      }
      if (negative) {
        seconds = -seconds;
        nanos = -nanos;
      }
      try {
        return normalizedDuration(seconds, nanos);
      } catch (IllegalArgumentException e) {
        throw new ParseException("Duration value is out of range.", 0);
      }
    }
  
    /** Create a Duration from the number of seconds. */
    public static Duration fromSeconds(long seconds) {
      return normalizedDuration(seconds, 0);
    }
  
    /**
     * Convert a Duration to the number of seconds. The result will be rounded towards 0 to the
     * nearest second. E.g., if the duration represents -1 nanosecond, it will be rounded to 0.
     */
    public static long toSeconds(Duration duration) {
      return checkValid(duration).getSeconds();
    }
  
    /** Create a Duration from the number of milliseconds. */
    public static Duration fromMillis(long milliseconds) {
      return normalizedDuration(
          milliseconds / MILLIS_PER_SECOND,
          (int) (milliseconds % MILLIS_PER_SECOND * NANOS_PER_MILLISECOND));
    }
  
    /**
     * Convert a Duration to the number of milliseconds. The result will be rounded towards 0 to the
     * nearest millisecond. E.g., if the duration represents -1 nanosecond, it will be rounded to 0.
     */
    public static long toMillis(Duration duration) {
      checkValid(duration);
      return checkedAdd(
          checkedMultiply(duration.getSeconds(), MILLIS_PER_SECOND),
          duration.getNanos() / NANOS_PER_MILLISECOND);
    }
  
    /** Create a Duration from the number of microseconds. */
    public static Duration fromMicros(long microseconds) {
      return normalizedDuration(
          microseconds / MICROS_PER_SECOND,
          (int) (microseconds % MICROS_PER_SECOND * NANOS_PER_MICROSECOND));
    }
  
    /**
     * Convert a Duration to the number of microseconds. The result will be rounded towards 0 to the
     * nearest microseconds. E.g., if the duration represents -1 nanosecond, it will be rounded to 0.
     */
    public static long toMicros(Duration duration) {
      checkValid(duration);
      return checkedAdd(
          checkedMultiply(duration.getSeconds(), MICROS_PER_SECOND),
          duration.getNanos() / NANOS_PER_MICROSECOND);
    }
  
    /** Create a Duration from the number of nanoseconds. */
    public static Duration fromNanos(long nanoseconds) {
      return normalizedDuration(
          nanoseconds / NANOS_PER_SECOND, (int) (nanoseconds % NANOS_PER_SECOND));
    }
  
    /** Convert a Duration to the number of nanoseconds. */
    public static long toNanos(Duration duration) {
      checkValid(duration);
      return checkedAdd(
          checkedMultiply(duration.getSeconds(), NANOS_PER_SECOND), duration.getNanos());
    }
  
    /** Add two durations. */
    public static Duration add(Duration d1, Duration d2) {
      checkValid(d1);
      checkValid(d2);
      return normalizedDuration(
          checkedAdd(d1.getSeconds(), d2.getSeconds()), checkedAdd(d1.getNanos(), d2.getNanos()));
    }
  
    /** Subtract a duration from another. */
    public static Duration subtract(Duration d1, Duration d2) {
      checkValid(d1);
      checkValid(d2);
      return normalizedDuration(
          checkedSubtract(d1.getSeconds(), d2.getSeconds()),
          checkedSubtract(d1.getNanos(), d2.getNanos()));
    }
  
    static Duration normalizedDuration(long seconds, int nanos) {
      if (nanos <= -NANOS_PER_SECOND || nanos >= NANOS_PER_SECOND) {
        seconds = checkedAdd(seconds, nanos / NANOS_PER_SECOND);
        nanos %= NANOS_PER_SECOND;
      }
      if (seconds > 0 && nanos < 0) {
        nanos += NANOS_PER_SECOND; // no overflow since nanos is negative (and we're adding)
        seconds--; // no overflow since seconds is positive (and we're decrementing)
      }
      if (seconds < 0 && nanos > 0) {
        nanos -= NANOS_PER_SECOND; // no overflow since nanos is positive (and we're subtracting)
        seconds++; // no overflow since seconds is negative (and we're incrementing)
      }
      Duration duration = Duration.newBuilder().setSeconds(seconds).setNanos(nanos).build();
      return checkValid(duration);
    }
  }
  